/Engine/Source/Developer/SkeletalMeshUtilitiesCommon/Public/LODUtilities.h
Reorder the material slot array to follow the base LOD section order. It will readjust all LOD section material index and LODMaterialMap.
static void ReorderMaterialSlotToBaseLod ( [USkeletalMesh](API\Runtime\Engine\Engine\USkeletalMesh) * SkeletalMesh )